This invention relates to a semi-conducting pyrolyzed glass fiber layer covering an insulated electrical conductor which prohibits the development of a corona discharge when an electrical potential exists between the conductor and region adjacent the exterior surface of the insulator.
In many electrical devices, an electrical potential exists between a conductor and the regions immediately adjacent the exterior surface of an insulator surrounding the conductor. In a high powered electrical apparatus such as a dynamoelectric machine, the stationary armature core is generally made of laminations which define a cylindrical bore and which also define circumferentially spaced radial slots opening into the bore and axially extending substantially the length of the stator core. Heavily insulated electrical windings, or armature bars, are disposed in the slots. A high electrical potential difference exists between the windings or armature bars and the members of this stator defining the slots which are at an electrical ground.